## Overview

This week we will complete our study of stings.

## Monday, February 14th

### Classwork

We'll begin class with a short quiz on the content in *Chapter 4: Strings*
from our text.

Then, given all the work she put into it, I would like to discuss the problem that Leila and Christopher worked on from the VCU programming contest, for which Leila did some extensive reflection:

To which I want to add some of my own:

- It is a lot easier to understand a problem like this when you can restate it with clear, precise, mathematical definitions, so let's do that.
- A subsequence of a given sequence is a sequence that can be derived from the given sequence by deleting some or no elements without changing the order of the remaining elements.
- A
monotonically increasing sequence is a sequence S such that
S
_{n}≤ S_{n+1}for all elements of the sequence. - We can define a
**strictly increasing sequence**as a sequence S such that S_{n}< S_{n+1}for all elements of the sequence.

We can now rewrite the task from *Problem D: A New Lottery Game* precisely
and succinctly:

Given a sequence of natural numbers, determine the number of strictly increasing subsequences of length 3 that can be derived from the sequence.

With that clear statement of the problem, a delightfully short Python solution to the problem was not too difficult to write. (You just gotta love Python! ;-)

### Homework

Find another programming problem from either the VCU or UMD problem sets that involves strings, and develop a solution to it in C.